Surface Energy Measurements of Graphite and Glass Filaments

The surface energies of graphite and glass filaments were determined by the Wilhelmy balance technique and two semi-empirical expressions. The work of adhesion of various thermoplastics on these filaments was then predicted. The technique successfully distinguished surface changes caused by processing variations. Polar matrix materials such as nylon 6,6 were predicted to adhere significantly better than nonpolar resins such as polyethylene. The notch sensitivity of composite plaques correlated with these predictions. However, there was no relationship in silane systems where wetting is not the primary mechanism for improved adhesion and tensile properties.